MOUNT RUSHMORE NATIONAL MEMORIAL, S.D. (Reuters) - President Bush accused the Democratic-led Senate on Thursday of tying the hands of his proposed Homeland Security Department while Senate Majority Leader Tom Daschle said the U.S. president was seeking "dictatorial powers" over the agency. With the stern granite faces of four presidents gazing down from the Mount Rushmore monument, Bush suggested the Senate was placing dangerous limits on his ability to protect the nation through the planned 170,000-strong agency whose creation he proposed after the Sept. 11 attacks. "I need the flexibility to be able to look at the American people and...